State a formula for the area of a spherical triangle with angles $\alpha, \beta, \gamma$.

Let $n \geqslant 3$. What is the area of a convex spherical $n$-gon with interior angles $\alpha_{1}, \ldots, \alpha_{n}$ ? Justify your answer.

Find the range of possible values for the interior angle of a regular convex spherical $n-g \mathrm{gn}$